LM25117 input timing of external clock

Kei Sato73562

Expert 2310 points

Other Parts Discussed in Thread: LM25117

Please tell me LM25117 input timing of external clock.

UVLO is used for ON/OFF of power up.

May I input an external clock, When UVLO is OFF?

For details, please check an attached file.

LM25117 Input timing of external clock .pptx

over 11 years ago

0 EricLee over 11 years ago

TI__Guru 58551 points

It is always recommended to apply the external clock earlier than UVLO>1.2V.

Regards,

0 Kei Sato73562 over 11 years ago in reply to EricLee

Expert 2310 points

Hi EricLee,

Thank you for reply.

Please teach me a reason.

If an external clock is inputted from before UVLO<1.2, it will synchronize from the time of Power up.

Is it because it cannot synchronize until an external clock enters, when it synchronizes after Power up?

0 EricLee over 11 years ago in reply to Kei Sato73562

TI__Guru 58551 points

LM25117 can be synchronized by the external clock even if the external clock is applied after power-on.

If you apply the external clock after power-on, there might be one (or two) ugly switching during the transition from internal clock to external clock.

Regards

Power management

Power management forum

LM25117 input timing of external clock